FROM THIS EPISODE

Manuel López Obrador has filled the streets of Mexico City with tens of thousands of political supporters. Now he’s threatening to use them to force a new presidential election. What are the chances of violent conflict? What are the possible consequences for the United States? Plus, more violence as Iraqis try to take charge of their security forces, and a political surprise that could be historic: former President Jimmy Carter may meet with the former President of Iran.

General George Casey, America's top military official in Iraq, said today that Iraqi security forces should be able to take over in 12 to 18 months. But Ambassador Zalmay Khalilzad has told the Los Angeles Times that if current levels of violence continue, the US "simply cannot achieve its goals." Patrick McDonnell is in Baghdad for the Times.

All the elements are in place for big trouble in the aftermath of Mexico's disputed presidential election. Manuel López Obrador appears to have lost to conservative Felipe Calderón, but says he'll declare himself the "legitimate" president of a "parallel" government. His claim that the official vote count was fraudulent has been rejected unanimously by the nation's top electoral court. The leftist supporters of the former Mayor of Mexico City already occupy the public venues where the conservative current president, Vicente Fox, plans traditional ceremonies on Friday. Can López Obrador make political life impossible and force another election? If Fox exerts his authority, will there be violence? What's the possible fallout North of the border?

Despite growing tension with the Islamic Republic of Iran, the Bush Administration has issued a visa to former President Mohammad Khatami. Though he no longer speaks for Iran, Khatami's two-week visit will demonstrate America's tradition of free speech--which does not exist in Iran itself. How long will he be here? Who will he see? What's the reaction of Iranians who fled their country to live in the US? Shaul Bakhash is a former journalist who left Iran in 1980.

Guests:Shaul Bakhash, Professor of Middle East History, George Mason University